Coating apparatus – Gas or vapor deposition – With treating means
Reexamination Certificate
1999-06-18
2001-09-18
Mills, Gregory (Department: 1763)
Coating apparatus
Gas or vapor deposition
With treating means
C156S345420, C118S7230AN, C118S715000
Reexamination Certificate
active
06289842
ABSTRACT:
BACKGROUND AND SUMMARY OF THE INVENTION
This application is directed to a fully integrated oxide Metal Organic Chemical Vapor Deposition (MOCVD) system having a plasma enhanced CVD showerhead.
Chemical Vapor Deposition (CVD) systems and Metal Organic Chemical Vapor Deposition (MOCVD) systems are widely used to manufacture electronic devices, such as integrated circuits by the sequential or simultaneous deposition of compounds upon a heated substrate, which is usually in the form of a wafer. The MOCVD growth mechanism proceeds by the decomposition of organometallic and/or metal hydride or other reactants at typically a heated surface of the substrate on which they are to be deposited. Equivalently, a relatively cool surface could be used to condense gas phase vapors. The reactants are transported to the surface in the gas phase by typically one or more carrier gases. The metals deposit on the surface, forming the desired compound and the undesirable by-products are pumped away in a gaseous form. Ideally, the reactants have vapor pressures of several torr and are liquids, e.g. TMAI or TMGa, or gases, e.g. SiH4, GeH4, CH4, WF6, A5H35:H9, . . . ) so that they may be easily transported to the reactor. However this is not true in all cases, for instance, Ba, Sr, Y, Cu, Er, Eu, and several other elements, which are needed for ferroelectrics, dielectrics, superconductors, luminescent and other films require high source temperatures and usually benefit from the use of a flash evaporator.
Silicon Carbide (SiC) based electronic devices are a rapidly developing technology and market. Key to these devices are production of high quality films and substrates. Recent work has indicated that a system capable of “accepted” deposition temperatures (through 1600° C. for epitaxy) and super high deposition temperatures (1800-2300° C. for substrate formation) should in combination produce superior device films. Superhigh temperature deposition capability greatly impacts all system operating parameters and components. Such items include: substrate heating, wafer holder construction, prevention of wafer levitation in an RF system, prevention of arcing in a high power RF system, reactor construction and cooling, gas and reactant inlets, flow manipulation, wafer rotation, materials of construction, minimization of etching, and physical layout of materials, among others. The present system is capable of depositing device films through the full temperature range (up to 2300° C.). The non-levitating wafer system assembly, heatable through 2300° C. without arcing or other failures is also compatible with in-situ plasma cleaning or plasma assisted deposition).
Another form of CVD deposition is where a substrate is cooled to condense a preactivated (by heat or plasma by example) material or an evaporated material. A prime example is parylene, which is evaporated at a low temperature(~150° C.), “cracked” at a high temperature (~680° C.) and then subsequently deposited on a cooled substrate (~room temperature to −50° C.). Such deposition techniques are compatible with the equipment described herein.
It is an object of the present invention to provide an improved Metal Organic Chemical Vapor Deposition System.
It is an object of the present invention to provide an improved Metal Organic Chemical Vapor Deposition System suitable for use at low deposition pressures (<0.1 to >100 Torr) and from low (<−50° C.) to high temperatures (up to 2300°).
It is an another object of the present invention to provide an improved Metal Organic Chemical Vapor Deposition System that is capable of depositing a wide variety of compounds and elements.
It is an object of the present invention to provide an improved Metal Organic Chemical Vapor Deposition System that employs a gas distribution unit that produces a uniform flow of carrier gas and reactants delivered to the reactor separately.
It is an object of the present invention to provide an improved Metal Organic Chemical Vapor Deposition System that has temperature control of the carrier and reactant gases at the gas distribution unit.
It is an object of the present invention to provide an improved Metal Organic Chemical Vapor Deposition System that can preclude (or facilitate) gas phase mixing of the reactants.
It is an object of the present invention to provide an improved Metal Organic Chemical Vapor Deposition System that includes an integral plasma generating unit that provides a plasma located in close distant, intermediate, or close proximity to the deposition surface.
It is an object of the present invention to provide an improved Metal Organic Chemical Vapor Deposition System that includes a rotating heating wafer holder that prevents wafer levitation during rotation when heated by high power RF.
It is an object of the present invention to provide an improved Metal Organic Chemical Vapor Deposition System that includes a rotating wafer holder that can be chilled or heated (resistively or by RF).
The present invention is directed to a Metal Organic Chemical Vapor Deposition (MOCVD) system particularly suitable for use at low deposition pressures and high or low temperatures. The system includes a reactor chamber that is isolated from the atmosphere and which can also be thermally isolated from the surrounding conditions. Located within the reactor chamber is a reactant gas distribution unit (showerhead) having a temperature control chamber, for controlling the temperature of the reactants, a chamber for providing a uniform flow of carrier gas and a gas distribution chamber which includes baffling which can preclude (or facilitate) gas phase mixing of the reactants. The gas distribution unit also includes an integral plasma generating electrode system for providing plasma enhanced deposition. Also located in the reactor chamber are either a RF wafer heating unit and a non-levitating rotating wafer carrier, a resistive heating element or a wafer heating and cooling assembly.
The present invention is capable of depositing a wide array of compounds and elements, including: phosphorous films (such as ZnSi
x
O
y
, ZnGe
x
O
y
, ZnIn
x
O
y
, ZnGa
x
O
y
, . . . ), dielectric films (such as BaSr
x
Ti
1-x
O), ferroelectric films, piezoelectric films, magnetic films, nitride films, carbide films, metal films (such as PbZr
x
Ti
1-x
O, SrBr
x
Ta
y
O
z
), superconducting films and the like.
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Alejandro Luz L.
Botjer William L
Mills Gregory
Structured Materials Industries Inc.
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